No experience cooking them together but the colander I have would work well to easily separate the the two. It has round holes, rather than slits, so quinoa will go right through with the oats staying put.

One suggestion about the quinoa is to rinse & re-rinse several times before cooking. Most boxes will say rinsing is not required, but I've found I prefer the results when I've rinsed before cooking.

You should try a batch, they need different amounts of liquid and are done at slightly different rates, so your oats will be more cooked than your quinoa, but maybe the fact that the oats need almost twice as much water will even things out? On the bright side, your breakfast will pack quite the nutritional punch.

The blog 101 cookbooks had a great mixed grains recipes (called grandma's grains, I think). Generally, if you have grains that require different cooking times like quinoa and steel cut oats, the shorter cooking grain will just break down and add creaminess.

I've been eating a mixture of oats, rolled barley, quinoa, and coarse cornmeal for breakfast lately and I love it! I just cook it like regular oatmeal and it turns out fine. I don't think you need to stress out about the different cooking times of the various grains.

I wonder if you could also grind it down to use it as a flour? I agree with others, though, that you could just cook em together for breakfast.

YUM, you have me hankering for a mixed grain hot breakfast! Be quiet grumbly belly.

Overnight in the crockpot with four cups water to every 1 cup grain should be just fine. I mix all kinds of whole grains that way. The steel-cut oats seem to need the most water (4 cups water to 1 cup grain) so I just use that ratio for everything and put at least a cup of steel-cut oats in and then however much of whatever else I want. My favorite combo so far is steel cut oats, spelt berries, kamut, and millet, but I've also tried amaranth (a little earthy for me), barley, and buckwheat. I usually add apples and raisins and a cinnamon stick and a little milk instead of some of the water.

Here's my recipe: Overnight Porridge

If you want to try something non-breakfasty, I think Bittman had some great savory ways to eat oats that you could easily apply:
http://www.seriouseats.com/recipes/2009/01/mark-bittmans-savory-oatmeal-with-scallions-and-soy-sauce-recipe.html
He had another with coconut that I tried which was really great! With the hearty quinoa, even better I bet.

Throw it all in a slow cooker and follow an overnight oatmeal recipie and see how that turns out.

I agree with the multiple breakfast suggestions... I've been doing just that lately, and it's super satisfying. My version is kamut, pearl barley, steel-cut oats and quinoa. Being mixed, the quinoa will probably overcook a bit, but mix it with a bit of applesauce and raisins and you'll never notice ;)

I have made a yummy flourless pancake recipe that has you soak steel cut oats and buckwheat groats overnight, but you can use any combination of grains this way (I have, and many are good). The recipe is here: http://www.cookusinterruptus.com/index.php?video_id=103

Yep! I actually eat steel cut oats and quinoa together quite often. My favorite way to prepare them is by soaking the duo overnight in a bit of water then I strain and rinse them in the morning and eat them raw with fruit and yogurt. Soooo good!

I've cooked them together following the steel cut oat directions. I often add dried fruit, nuts and ginger.

why not treat it as savory oatmeal, after cooking on the stove-top mix in finely chopped bacon and green onions along with a little parmesan cheese? Or treat it like a base for fried rice and toss in any bits and pieces in your fridge as your taste buds desire. Sounds like a fun challenge!!!